I am using Adobe reader. The font is just one of the one's available on my MAC. I did a work around by using Ariel font for the speech marks, and it exported just fine. So there is something about DIN-Medium which is causing this.

Do you have a full version of Acrobat? If you do you can check the font usage to see if all the fonts are embedded. You can also use the Text Touch-up (called Edit Text in newer versions of Acrobat, I think) tool to select the text and check the properties to see what font is listed and if it is embedded for the wrong glyphs.

I could do but i have changed the fonts now to do a work around...shall I share the PDF? I just tried to insert the image but an error message appeared saying the file was too big...it's only 253kb...so not sure what that is all about. If you give you email address, I'll email it.

I'm seeing quotation marks here, but not necessarily the correct ones (I'm quite sure the single quotes around ESI in the payment form are incorrect).

As I suspected, there are fonts that are not embedded -- the DIN Medium and Bold. According to Find Font in ID, these are version 1.0 and TrueType, so most likely very old and lacking the permission bit that ID looks for when embedding. The italic versions appear to be embedded, but for versioning they say Macromedia Fontographer, so I think they are home-brew. You should consider buying a current OpenType version.